This function produces SMILES that correspond what Daylight Chemical Information
Systems term an ‘absolute‘ SMILES

Note that the canonical SMILES generated by this function remains
dependent on the state of the molecule, especially its aromaticity
state (see examples in Aromaticity Models in OEChem TK section).
Thus, to generate a canonical smiles suitable for purposes
such as a database key, the user must assure that the state of
the molecule has been standardized.
In particular, aromaticity should be perceived according to the preferred model.

Furthermore, whether OEWriteMolecule or
OECreateIsoSmiString is used, the canonical SMILES generated depends on
the current stereo specifications for the molecule.
If the goal is a canonical isomeric SMILES which is unique for all representations
of an equivalent stereoisomer, i.e., for use as a database key, it is the user’s
responsibility to assure that the stereochemical state of the molecule has been
rationalized and standardized, using methods such as:

The OECreateIsoSmiString is rigorously tested to ensure
that it generates unique string representations of molecules.
This test involves randomly reordering the atoms and bonds of molecules
and confirming that this has no effect on the SMILES generated by the
OECreateIsoSmiString function.